JPH04366380A - Low temperature cabinet - Google Patents

Abstract

PURPOSE:To provide a low temperature cabinet capable of protecting a compressor from over load and restarting the compressor immediately after a power source is reconnected. CONSTITUTION:There is installed a cooling device 7 which comprises a refrigerant circuit having a compressor connected with an AC power source (AC 200V). A timer counts a specified period of time from the suspension of the compressor and prohibits the restarting of the compressor. The AC power source is connected with a battery 32 by way of a charge circuit 33. The timer continuous its counting operation supplied by the battery in spite of the cut off of the AC power source.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-temperature refrigerator equipped with a timer for prohibiting restart of a compressor for a predetermined period after it has been stopped.

0002

[Prior Art] Conventionally, this type of low-temperature storage has a compressor, a condenser,
It is equipped with a cooling device consisting of a well-known refrigerant circuit composed of a pressure reducer, a cooler, etc., and is configured to cool the storage chamber with the cooler. Immediately after the compressor stops, there is a large pressure difference between the high pressure side and the low pressure side in the refrigerant circuit, and if the compressor is restarted in this state, an excessive load will be applied to the compressor.
Damage to the compressor may occur due to motor locking, etc.

[0003] For this reason, a delay timer has conventionally been provided that prohibits restarting the compressor for a predetermined period of time, for example, three minutes in most cases, after the compressor has stopped.

0004

[Problems to be Solved by the Invention] However, in conventional low-temperature refrigerators, the power source for the timer is either taken from the AC power source or used after rectifying it, so it is difficult to avoid problems due to disconnection of the AC power source, such as when the outlet is accidentally unplugged. If the compressor is stopped, the timer begins counting when power is reconnected.

Therefore, even if the AC power supply is cut off and the compressor is stopped and then reconnected, for example, two minutes later, as shown in FIG. 7, the start-up of the compressor is delayed for three minutes after the connection. That is, even though more than three minutes have passed since the compressor was stopped and the pressure difference in the refrigerant circuit has sufficiently decreased to a safe value, startup is prohibited for five minutes after the compressor has been stopped. As described above, regardless of the pressure state within the refrigerant circuit, the compressor is prohibited from starting for three minutes after the power is connected, and there is the inconvenience that the compressor does not start cooling immediately after the power is turned on.

[0006] The present invention has been made to solve the above problems, and an object thereof is to provide a low-temperature refrigerator that can restart the compressor quickly after reconnecting the power supply while preventing the compressor from being overloaded. shall be.

[0007]

[Means for Solving the Problems] The low-temperature refrigerator R of the present invention includes a cooling device 7 consisting of a refrigerant circuit having a compressor 8 connected to an alternating current power source (AC 200V), and a cooling device 7 that is connected to an alternating current power source (AC200V) for a predetermined period of time after the compressor 8 is stopped. a timer A that prohibits the restart of the compressor 8, and a storage battery 3 connected to an AC power source via a charging circuit 33.
2, and timer A is equipped with
It is configured to continue counting by being supplied with power from a storage battery 32.

[0008]

According to the present invention, even if the AC power supply is cut off, timer A is supplied with power from the storage battery 32, so that the timer A can continue counting the predetermined period after the AC power supply is cut off.

[0009]

Embodiments Next, embodiments of the present invention will be explained based on the drawings. FIG. 1 is a block diagram of an electric circuit, and FIG. 2 is a longitudinal sectional view of the low-temperature refrigerator R.

The low-temperature refrigerator R includes a main body 1 made of a heat-insulating box, a storage chamber 2 formed in the main body 1 for storing articles,
A door 3 that opens and closes the storage room 2, a cold storage room 4 that communicates with the storage room 2 via a duct 5, a cold storage agent 6 stored in the cold storage room 4, and a cooling device 7 that cools the cold storage agent 6. It is configured. Here, the cold storage agent 6 has a freezing and melting temperature Ts of -
Use one at 25°C.

The cooling device 7 includes a compressor 8, a condenser 12, a capillary tube 11, and a cool storage agent 6 in the cool storage chamber 4.
It is composed of a cooler 10 disposed so as to be in close thermal contact with an accumulator 9, a refrigerant circuit in which an accumulator 9 is sequentially connected in an annular manner, and a condenser blower 13. Further, the air cooled by the cool storage agent 6 is sent to the storage room 2 via the duct 5 by a DC fan motor 14 serving as a blowing means.

The air in the storage chamber 2 is supplied to the cold storage chamber 4 from the suction port 15.
The air from the cold storage chamber 4 is blown out from the outlet 16 of the duct 5 into the storage chamber 2. A cool storage agent temperature sensor 17 is attached to the cool storage agent 6 as a temperature detection means for detecting the temperature thereof. Further, the air outlet 16 is provided with an internal temperature sensor 1 that detects the temperature of the cold air blown into the storage room 2.
8 is provided. Furthermore, the temperature of the condenser 12 is detected by a condenser temperature sensor 19.

Casters 20 are attached to the bottom of the main body 1, and bumpers 21 are attached to the upper and lower ends of the outer peripheral surface of the main body 1. Further, a machine room 22 is formed in the rear corner of the lower part of the main body 1, and a compressor 8, a storage battery, etc., which will be described later, are housed therein. still,
In this embodiment, in order to obtain sufficient cooling capacity, two cooling devices 7 and two DC fan motors 14 each having the same size are installed.

In FIG. 1, a rectifier circuit 31 as a power supply circuit is connected to the a contact point of a switching relay 36, and the output of a storage battery 32 connected to a charging circuit 33 is connected to a relay coil Ry.
It is connected to the B contact of the switching relay 36 via the contact No. 6. The switching relay 36 functions as a switching means for switching the power source of a microcomputer (hereinafter referred to as a microcomputer) 46 constituting the control unit between an AC power source (200 VAC) and the storage battery 32. That is, the common contact c of the switching relay 36 is connected to the microcomputer 46, and the contact is closed to a contact when AC power is connected, and is closed to contact b when AC power is disconnected. As a result, the microcomputer 46 connects the AC power source to the AC power source, and disconnects the AC power source from the storage battery 32.
It works as a power source.

The storage battery 32 includes a resistor 3 as a current sensor.
4 are connected in series and output a voltage proportional to the charging current. Further, a voltage monitoring circuit 35 for monitoring the voltage of the storage battery 32 is connected to the common contact c of the switching relay 36.
The output is input to the microcomputer 46. The voltages generated by the cool storage agent temperature sensor 17, the internal temperature sensor 18, the condenser temperature sensor 19, and the resistor 34, which are composed of transistor sensors, are amplified by amplifier circuits 37, 38, 39, and 40, respectively, and are all sent to the microcomputer 46. is input. Furthermore, the output of the negative phase detection circuit 41 that detects the connection state of the connected three-phase AC power source is also input to the microcomputer 46.

Compressor motor 42 of two compressors 8
, 43 and the reverse phase detection circuit 41, the relay coils 44 and 45 switch contacts (not shown) to bring the AC power supply into a normal connection state, and are respectively relay coils Ry2.
, Ry3, Ry4, and Ry5 to the AC power source. The DC fan motors 14, 14 are connected to a common contact c of a switching relay 36 via a contact of a relay coil Ry1. These relay coils Ry1, Ry2
, Ry3, Ry4, Ry5, and Ry6 are connected to the output of the microcomputer 46, and the microcomputer 46 opens and closes each contact by controlling energization of these, and controls the operation and stopping of the compressor 8 and DC fan motor 14 as described later. do. Similarly, the microcomputer 46 also controls switching between normal phase and negative phase, and discharge control of the storage battery 32.

Here, like the microcomputer 46, when the DC fan motor 14 is connected to an AC power source, it operates using the AC power source via the rectifier circuit 31 and the switching relay 36, and when the AC power source is disconnected, it operates using the storage battery 32 as a power source. . That is, during the cold storage operation to freeze the cold storage agent 6, the DC fan motor 14 uses the output of the rectifier circuit 31 as a power source, and the storage battery 32 and charging circuit 33 are not used.

Further, a switch input line from an operation panel 47 provided with input means for inputting signals to the microcomputer 46 and various display means and a display output line to the operation panel 47 are connected to the microcomputer 46 . Furthermore, the output of the rectifier circuit 31 is connected to the microcomputer 4 via a power signal line 49.
6, and based on this, the microcomputer 46 determines whether or not there is an AC power source.

Next, the operation will be explained. When the low-temperature refrigerator R is connected to an alternating current power source (AC200V) and the microcomputer 46 is powered on for the first time, the setting operation states of switches SW1 to SW4, which are input means provided on the operation panel 47, are read. Here, the operation panel 47 is provided with a refrigerator switch SW for instructing the start of internal cooling.
1. Temperature selection switch SW2 that selects the internal temperature to +5°C, which is the refrigeration temperature; Temperature selection switch SW3, which selects the freezing temperature to 0°C; and Temperature selection switch SW4, which selects the freezing temperature to -18°C. LED4 to LED6,
A display section 48 consisting of two 7-segment LEDs, S
When any one of SW2 to SW4 is operated, the microcomputer 46 lights up the LED4 to LED6 corresponding to the selected temperature. Further, the microcomputer 46 detects that the low-temperature refrigerator R is connected to the AC power source based on the output from the power signal line 49.

FIG. 3 shows temperature changes and operations of each part during operation, and FIGS. 4 and 5 show flowcharts of the control program of the microcomputer 46. At the delivery base, when the low-temperature warehouse R is connected to an alternating current power source (AC200V), charging of the storage battery 32 is started. Also, on the operation panel 47, S
It is assumed that W4 is operated and -18° C. is designated as the internal temperature setting Tc. The microcomputer 46 has a switching relay 36
Power is supplied from the rectifier circuit 31 through the a contact of the power supply, and at the same time as this power supply is supplied, it is determined in step 50 whether or not the cool storage agent temperature sensor 17 is short-circuited, and if it is not short-circuited, the cold storage It is then determined whether or not the agent temperature sensor 17 is disconnected. If there is no failure, it is determined in step 52 whether or not the compressor 8 is currently in operation;
Since it is stopped, the temperature of the cold storage agent 6 is -3 in step 53.
It is determined whether the temperature is 5° C. or higher, and since the temperature is high at the start of operation, the compressor 8 is operated in step 54. As a result, Figure 3
cold storage operation is started. Note that a short circuit or disconnection of the cool storage agent temperature sensor 17 can be determined by an abnormality in the output potential from the sensor.

If the compressor 8 is in operation in step 52, it is determined in step 55 whether the temperature of the refrigerant 6 is below -37°C, and if it is below, the compressor 8 is operated in step 56.
stop. As long as the cool storage agent temperature sensor 17 is normal and the AC power source (AC 200V) is connected, the compressor 8 is repeatedly operated and stopped under the above control.

In step 57, a subroutine for determining the completion of freezing of the cool storage agent 6 and the completion of charging of the storage battery 32 is executed. That is, there are two freezing determination conditions for the cold storage agent 6 here. One is that the temperature of the cold storage agent 6 based on the output of the cold storage agent temperature sensor 17 is -29 degrees Celsius lower than the freezing and melting temperature of -25 degrees Celsius. ℃ or below for more than 9 hours,
The other is -3, where the temperature of cold storage agent 6 is 7°C lower than -25°C.
This means that the temperature remained below 2°C for 10 minutes or more. If either one of these two conditions is satisfied, freezing of the cold storage agent 6 is considered to have been completed.

The charging state of the storage battery 32 is determined by inputting the voltage generated by the resistor 34 and calculating the charging current flowing through the storage battery 32 from that value. Consider it completed. When all of these steps are completed, the microcomputer 46 turns on the LED 2 to indicate that the cold storage operation is ready.

Next, in step 58, the refrigerator switch S
It is determined whether W1 has been pressed or not, and if it has not been pressed, it is determined in step 59 whether the freezing and charging have been completed, and since neither freezing nor charging has been completed since the power has just been turned on here, step 64 At this point, the DC fan motor 14 is stopped.

The conventional cold storage operation operation will be explained based on FIG. 3. The temperature of the cold storage agent 6 rapidly decreases due to the operation of the compressor 8, and the freezing temperature of the cold storage agent 6 reaches Ts about 3.5 hours after the start of operation. It reaches -25°C. However, due to the supercooling phenomenon of the cool storage agent 6, the cool storage agent 6 does not freeze immediately, and its temperature continues to fall further. Then, the temperature of the cold storage agent 6 is about -
Freezing begins when the temperature reaches 31°C, and the temperature of the cold storage agent 6 is approximately -
Return to 25°C. While the cold storage agent 6 is frozen, its temperature is -25
The temperature remains constant at ℃, but once the freezing ends, the temperature starts to drop again and becomes lower than -32℃.

In the process of the above-described operation, when the freezing and charging completion determination conditions of step 57 are satisfied, the process proceeds from step 59 to step 60, where it is determined whether the DC fan motor 14 is currently operating, and since it is not, step 61 is performed. The temperature of the storage compartment 2 based on the internal temperature sensor 18 is the set temperature Tc.
It is determined whether the temperature is +1°C or higher, and since the temperature of the storage chamber 2 is high here, the DC fan motor 14 is operated in step 63.
The cool storage operation is ended and the refrigerator internal cooling operation is started. This DC
By operating the fan motor 14, latent heat of fusion of the cool storage agent 6 or cold air cooled by the cooler 10 is circulated into the storage chamber 2, thereby cooling the storage chamber 2.

When the temperature of the storage chamber 2 based on the internal temperature sensor 18 reaches the set temperature Tc by this cooling, the process proceeds from steps 60 and 62 to step 64, and the DC fan motor 14 is stopped. In this way, DC fan motor 1
4 is repeatedly operated and stopped, and the temperature of storage room 2 is -18
Maintained around ℃.

Here, when the refrigerator switch SW1 is pressed during the cold storage operation, the cold storage agent 6 freezes or the storage battery 32 freezes.
Step 58
The process then proceeds to step 60, so that the cold storage operation is shifted to the internal cooling operation. This is performed when it is necessary to cool the food in the storage room 2 while freezing the cold storage agent 6.

[0029] Also, during the above-mentioned cold storage operation or refrigerator cooling operation, in step 50 or 51, the cold storage agent temperature sensor 17 is
If a failure is discovered, the process proceeds to step 65. In step 65, it is determined whether or not the DC fan motor 65 is in operation. If it is not in operation, in step 66, the temperature of the storage compartment 2 based on the internal temperature sensor 18 is set to the set temperature Tc + 1°C.
(i.e. -17°C) or higher, and if the temperature is higher than that, the compressor 8 and the DC fan motor 14 are
is operated, and when the temperature of the storage compartment 2 based on the internal temperature sensor 18 reaches the set temperature Tc due to this cooling, step 6
Step 5 and step 67 proceed to step 69, where the compressor 8 and DC fan motor 14 are stopped.

That is, if a failure such as a short circuit or disconnection occurs in the cold storage agent temperature sensor 17, it will be impossible to determine whether the freezing of the cold storage agent 6 is complete, but even in that case, instead of stopping the entire system, the compressor 8 and the DC fan motor 14 are automatically controlled by comparing the temperature of the storage compartment 2 based on the internal temperature sensor 18 and the set temperature Tc, that is, the control of general refrigerator operation is performed. The DC fan motor 14 is repeatedly operated and stopped, and the temperature of the storage chamber 2 is maintained at around -18° C., which is the set temperature Tc. Therefore, although freezing control of the cold storage agent 6 is not performed, even if foods are stored in the storage chamber 2, at least the preservation of these foods is achieved.

Here, the microcomputer 46 displays the temperature inside the storage chamber 2 and the set temperature on the display section 48 during normal operation.
When a failure occurs in the cool storage agent temperature sensor 17, an error message such as E5 is displayed in the case of a disconnection, and E6 is displayed in the case of a short circuit. This notifies the user of the occurrence of a failure.

Furthermore, in this type of cooling device 7, immediately after the compressor 8 is stopped, there is a large pressure difference between the high pressure side and the low pressure side in the refrigerant circuit, and if the compressor 8 is restarted in this state, an overload will occur. To prevent starting failure and damage the compressor 8, restarting the compressor 8 is prohibited for three minutes after it is stopped. This prohibition of restarting is performed by a delay timer A as a function of the microcomputer 46, which will be described later, but the compressor 8 can be stopped by the microcomputer 46 under control in step 56 or 69, or by cutting off the AC power supply (200 VAC). There are some cases where it stops due to this. The feature of the present invention is particularly related to the case where the AC power supply is cut off, and only the prohibition of operation of the compressor 8 for 3 minutes after the AC power supply (AC 200V) is cut off will be explained using the flowchart of FIG.

That is, in step 75 it is determined whether the prohibition flag is set, and since it is reset in the initial state, it is determined in step 76 whether or not the AC power supply has been disconnected. When the AC power supply is cut off due to the outlet of the low-temperature refrigerator R being accidentally pulled out, etc., a prohibition flag is set in steps 76 and 77, a timer A that the microcomputer 46 has as a function is counted in step 78, and a count is made in step 79. It is determined whether the count of timer A has reached 3 minutes, and the prohibition flag and timer A are reset in step 80 after the count is started, that is, after 3 minutes have elapsed since the AC power supply was first disconnected. On the other hand, in steps 54 and 68 of the flowchart of FIG. 4, setting and resetting of this prohibition flag is actually monitored, and step 5
When starting the compressor 8 in step 4 or 68, the state of this prohibition flag is checked, and if the prohibition flag is reset, it starts as is, but if the prohibition flag is set, the microcomputer 46 Machine 8 does not start. This prevents the compressor 8 from restarting immediately after the AC power supply is cut off.

Here, even if the AC power supply is cut off, the power supply to the microcomputer 46 continues to be supplied from the storage battery 32 as shown in FIG. ing. Therefore,
Even if the AC power source is disconnected and reconnected two minutes later as shown in FIG. 6, the inhibition of starting the compressor 8 is lifted exactly three minutes after the disconnection and the compressor 8 stops. As a result, the prohibition is canceled two minutes earlier than in the conventional case shown in FIG. Furthermore, even when AC power is turned on to the low-temperature refrigerator R that has returned after delivery, three minutes have already passed, but in the past, you had to wait for three minutes, but with the present invention, it can be turned on immediately. The compressor 8 can now be started. Generally, the timer A of the microcomputer 46 operates to set the above-mentioned prohibition flag even when the compressor 8 is stopped by temperature control as described above. Therefore, in the timing chart of FIG. 6, even if the compressor 8 is stopped 1 minute before the AC power is cut off, the time will be 3 minutes when the power is connected 2 minutes after the cut, so the compressor 8 The ban on starting will be lifted.

After the cold storage operation and refrigerator cooling operation as described above, articles such as foods are stored in the low-temperature refrigerator R, disconnected from the AC power source, and loaded onto a delivery vehicle. When the low-temperature refrigerator R is no longer supplied with AC power (AC power OFF), the cold storage agent 6
A cold storage operation is started in which the storage chamber 2 is cooled by the latent heat of fusion. During the cold storage operation, the microcomputer 46 and the DC fan motor 14 are supplied with power by discharging the storage battery 32 by switching the changeover switch 36 to the b contact. Further, the DC fan motor 14 is controlled by the microcomputer 46, and the temperature of the storage compartment 2 measured by the internal temperature sensor 18 is set to Tc+1.
It starts when the temperature rises to ℃ and stops when it falls to Tc. As a result, the inside of the storage chamber 2 is maintained at around -18°C. It is assumed that the contacts of the relay switch Ry6 are closed.

This cold storage operation ends five hours after the AC power supply is turned off, and thereafter the DC fan motor 14 is also completely stopped. These five hours are determined as enough time for the delivery vehicle to complete the delivery.

[0037] When the low-temperature refrigerator R returns to the delivery base after this delivery, several hours have naturally passed since the start of the cold storage operation. That is, at least three minutes have passed since the AC power supply was cut off, and the microcomputer 46 is supplied with power from the storage battery 32 even during the cold storage operation, and the timer A has completed counting. Therefore, if you connect an AC power source to the returned low-temperature refrigerator R,
Since the compressor 8 can be started immediately, usability is significantly improved during busy times.

[0038]

According to the present invention, the timer is supplied with power from the storage battery regardless of whether the AC power source is disconnected, so the timer continues to count the predetermined period after the AC power source is disconnected. Therefore, if the compressor stops due to disconnection of the AC power supply and the AC power supply is reconnected during the predetermined period, only the remaining period has elapsed since the reconnection, or if the compressor is reconnected after the predetermined period has elapsed. It becomes possible to restart the compressor immediately after that, achieving a rapid start of cooling and significantly improving usability.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an electric circuit.

FIG. 2 is a longitudinal cross-sectional view of the low-temperature refrigerator.

FIG. 3 is a characteristic diagram illustrating temperature changes and operations during operation.

FIG. 4 is a flowchart of a control program.

FIG. 5 is a flowchart of a control program.

FIG. 6 is a timing chart illustrating operating states of an AC power source and a compressor.

FIG. 7 is a timing chart corresponding to FIG. 6 in the case of a conventional low-temperature refrigerator.

[Explanation of symbols]

7 Cooling device 8 Compressor 32 Storage battery 33 Charging circuit R Low temperature storage

Claims (1)

[Claims] 1. A cooling device comprising a refrigerant circuit having a compressor connected to an AC power source; a timer for counting a predetermined period from the stop of the compressor and prohibiting restart of the compressor;
and a storage battery connected to the AC power source via a charging circuit, and the timer is configured to:
A low-temperature refrigerator that continues the counting by being supplied with power from the storage battery.